<?php
    /**
     * PHPExcel
     * Copyright (c) 2006 - 2015 PHPExcel
     * This library is free software; you can redistribute it and/or
     * modify it under the terms of the GNU Lesser General Public
     * License as published by the Free Software Foundation; either
     * version 2.1 of the License, or (at your option) any later version.
     * This library is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     * Lesser General Public License for more details.
     * You should have received a copy of the GNU Lesser General Public
     * License along with this library; if not, write to the Free Software
     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
     * @category   PHPExcel
     * @package    PHPExcel_Shared
     * @copyright  Copyright (c) 2006 - 2015 PHPExcel (http://www.codeplex.com/PHPExcel)
     * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
     * @version    ##VERSION##, ##DATE##
     */
    defined('IDENTIFIER_OLE') || define('IDENTIFIER_OLE', pack('CCCCCCCC', 0xd0, 0xcf, 0x11, 0xe0, 0xa1, 0xb1, 0x1a, 0xe1));

    class PHPExcel_Shared_OLERead {
        const IDENTIFIER_OLE = IDENTIFIER_OLE;
        // OLE identifier
        const BIG_BLOCK_SIZE = 0x200;
        // Size of a sector = 512 bytes
        const SMALL_BLOCK_SIZE = 0x40;
        // Size of a short sector = 64 bytes
        const PROPERTY_STORAGE_BLOCK_SIZE = 0x80;
        // Size of a directory entry always = 128 bytes
        const SMALL_BLOCK_THRESHOLD = 0x1000;
        // Minimum size of a standard stream = 4096 bytes, streams smaller than this are stored as short streams
        const NUM_BIG_BLOCK_DEPOT_BLOCKS_POS = 0x2c;
        // header offsets
        const ROOT_START_BLOCK_POS        = 0x30;
        const SMALL_BLOCK_DEPOT_BLOCK_POS = 0x3c;
        const EXTENSION_BLOCK_POS         = 0x44;
        const NUM_EXTENSION_BLOCK_POS     = 0x48;
        const BIG_BLOCK_DEPOT_BLOCKS_POS  = 0x4c;
        const SIZE_OF_NAME_POS            = 0x40;
        // property storage offsets (directory offsets)
        const TYPE_POS        = 0x42;
        const START_BLOCK_POS = 0x74;
        const SIZE_POS        = 0x78;
        public  $wrkbook                    = null;
        public  $summaryInformation         = null;
        public  $documentSummaryInformation = null;
        private $data                       = '';

        /**
         * Read the file
         * @param $sFileName string Filename
         * @throws PHPExcel_Reader_Exception
         */
        public function read($sFileName) {
            // Check if file exists and is readable
            if (!is_readable($sFileName)) {
                throw new PHPExcel_Reader_Exception("Could not open " . $sFileName . " for reading! File does not exist, or it is not readable.");
            }
            // Get the file identifier
            // Don't bother reading the whole file until we know it's a valid OLE file
            $this->data = file_get_contents($sFileName, false, null, 0, 8);
            // Check OLE identifier
            if ($this->data != self::IDENTIFIER_OLE) {
                throw new PHPExcel_Reader_Exception('The filename ' . $sFileName . ' is not recognised as an OLE file');
            }
            // Get the file data
            $this->data = file_get_contents($sFileName);
            // Total number of sectors used for the SAT
            $this->numBigBlockDepotBlocks = self::getInt4d($this->data, self::NUM_BIG_BLOCK_DEPOT_BLOCKS_POS);
            // SecID of the first sector of the directory stream
            $this->rootStartBlock = self::getInt4d($this->data, self::ROOT_START_BLOCK_POS);
            // SecID of the first sector of the SSAT (or -2 if not extant)
            $this->sbdStartBlock = self::getInt4d($this->data, self::SMALL_BLOCK_DEPOT_BLOCK_POS);
            // SecID of the first sector of the MSAT (or -2 if no additional sectors are used)
            $this->extensionBlock = self::getInt4d($this->data, self::EXTENSION_BLOCK_POS);
            // Total number of sectors used by MSAT
            $this->numExtensionBlocks = self::getInt4d($this->data, self::NUM_EXTENSION_BLOCK_POS);
            $bigBlockDepotBlocks = [];
            $pos                 = self::BIG_BLOCK_DEPOT_BLOCKS_POS;
            $bbdBlocks = $this->numBigBlockDepotBlocks;
            if ($this->numExtensionBlocks != 0) {
                $bbdBlocks = (self::BIG_BLOCK_SIZE - self::BIG_BLOCK_DEPOT_BLOCKS_POS) / 4;
            }
            for ($i = 0; $i < $bbdBlocks; ++$i) {
                $bigBlockDepotBlocks[$i] = self::getInt4d($this->data, $pos);
                $pos                     += 4;
            }
            for ($j = 0; $j < $this->numExtensionBlocks; ++$j) {
                $pos          = ($this->extensionBlock + 1) * self::BIG_BLOCK_SIZE;
                $blocksToRead = min($this->numBigBlockDepotBlocks - $bbdBlocks, self::BIG_BLOCK_SIZE / 4 - 1);
                for ($i = $bbdBlocks; $i < $bbdBlocks + $blocksToRead; ++$i) {
                    $bigBlockDepotBlocks[$i] = self::getInt4d($this->data, $pos);
                    $pos                     += 4;
                }
                $bbdBlocks += $blocksToRead;
                if ($bbdBlocks < $this->numBigBlockDepotBlocks) {
                    $this->extensionBlock = self::getInt4d($this->data, $pos);
                }
            }
            $pos                 = 0;
            $this->bigBlockChain = '';
            $bbs                 = self::BIG_BLOCK_SIZE / 4;
            for ($i = 0; $i < $this->numBigBlockDepotBlocks; ++$i) {
                $pos = ($bigBlockDepotBlocks[$i] + 1) * self::BIG_BLOCK_SIZE;
                $this->bigBlockChain .= substr($this->data, $pos, 4 * $bbs);
                $pos                 += 4 * $bbs;
            }
            $pos                   = 0;
            $sbdBlock              = $this->sbdStartBlock;
            $this->smallBlockChain = '';
            while ($sbdBlock != -2) {
                $pos = ($sbdBlock + 1) * self::BIG_BLOCK_SIZE;
                $this->smallBlockChain .= substr($this->data, $pos, 4 * $bbs);
                $pos                   += 4 * $bbs;
                $sbdBlock = self::getInt4d($this->bigBlockChain, $sbdBlock * 4);
            }
            // read the directory stream
            $block       = $this->rootStartBlock;
            $this->entry = $this->_readData($block);
            $this->readPropertySets();
        }

        /**
         * Read 4 bytes of data at specified position
         * @param string $data
         * @param int    $pos
         * @return int
         */
        private static function getInt4d($data, $pos) {
            // FIX: represent numbers correctly on 64-bit system
            // http://sourceforge.net/tracker/index.php?func=detail&aid=1487372&group_id=99160&atid=623334
            // Hacked by Andreas Rehm 2006 to ensure correct result of the <<24 block on 32 and 64bit systems
            $_or_24 = ord($data[$pos + 3]);
            if ($_or_24 >= 128) {
                // negative number
                $_ord_24 = -abs((256 - $_or_24) << 24);
            } else {
                $_ord_24 = ($_or_24 & 127) << 24;
            }
            return ord($data[$pos]) | (ord($data[$pos + 1]) << 8) | (ord($data[$pos + 2]) << 16) | $_ord_24;
        }

        /**
         * Read a standard stream (by joining sectors using information from SAT)
         * @param int $bl Sector ID where the stream starts
         * @return string Data for standard stream
         */
        private function _readData($bl) {
            $block = $bl;
            $data  = '';
            while ($block != -2) {
                $pos   = ($block + 1) * self::BIG_BLOCK_SIZE;
                $data  .= substr($this->data, $pos, self::BIG_BLOCK_SIZE);
                $block = self::getInt4d($this->bigBlockChain, $block * 4);
            }
            return $data;
        }

        /**
         * Read entries in the directory stream.
         */
        private function readPropertySets() {
            $offset = 0;
            // loop through entires, each entry is 128 bytes
            $entryLen = strlen($this->entry);
            while ($offset < $entryLen) {
                // entry data (128 bytes)
                $d = substr($this->entry, $offset, self::PROPERTY_STORAGE_BLOCK_SIZE);
                // size in bytes of name
                $nameSize = ord($d[self::SIZE_OF_NAME_POS]) | (ord($d[self::SIZE_OF_NAME_POS + 1]) << 8);
                // type of entry
                $type = ord($d[self::TYPE_POS]);
                // sectorID of first sector or short sector, if this entry refers to a stream (the case with workbook)
                // sectorID of first sector of the short-stream container stream, if this entry is root entry
                $startBlock = self::getInt4d($d, self::START_BLOCK_POS);
                $size = self::getInt4d($d, self::SIZE_POS);
                $name = str_replace("\x00", "", substr($d, 0, $nameSize));
                $this->props[] = [
                    'name'       => $name,
                    'type'       => $type,
                    'startBlock' => $startBlock,
                    'size'       => $size
                ];
                // tmp helper to simplify checks
                $upName = strtoupper($name);
                // Workbook directory entry (BIFF5 uses Book, BIFF8 uses Workbook)
                if (($upName === 'WORKBOOK') || ($upName === 'BOOK')) {
                    $this->wrkbook = count($this->props) - 1;
                } elseif ($upName === 'ROOT ENTRY' || $upName === 'R') {
                    // Root entry
                    $this->rootentry = count($this->props) - 1;
                }
                // Summary information
                if ($name == chr(5) . 'SummaryInformation') {
                    //                echo 'Summary Information<br />';
                    $this->summaryInformation = count($this->props) - 1;
                }
                // Additional Document Summary information
                if ($name == chr(5) . 'DocumentSummaryInformation') {
                    //                echo 'Document Summary Information<br />';
                    $this->documentSummaryInformation = count($this->props) - 1;
                }
                $offset += self::PROPERTY_STORAGE_BLOCK_SIZE;
            }
        }

        /**
         * Extract binary stream data
         * @return string
         */
        public function getStream($stream) {
            if ($stream === null) {
                return null;
            }
            $streamData = '';
            if ($this->props[$stream]['size'] < self::SMALL_BLOCK_THRESHOLD) {
                $rootdata = $this->_readData($this->props[$this->rootentry]['startBlock']);
                $block = $this->props[$stream]['startBlock'];
                while ($block != -2) {
                    $pos        = $block * self::SMALL_BLOCK_SIZE;
                    $streamData .= substr($rootdata, $pos, self::SMALL_BLOCK_SIZE);
                    $block = self::getInt4d($this->smallBlockChain, $block * 4);
                }
                return $streamData;
            } else {
                $numBlocks = $this->props[$stream]['size'] / self::BIG_BLOCK_SIZE;
                if ($this->props[$stream]['size'] % self::BIG_BLOCK_SIZE != 0) {
                    ++$numBlocks;
                }
                if ($numBlocks == 0) {
                    return '';
                }
                $block = $this->props[$stream]['startBlock'];
                while ($block != -2) {
                    $pos        = ($block + 1) * self::BIG_BLOCK_SIZE;
                    $streamData .= substr($this->data, $pos, self::BIG_BLOCK_SIZE);
                    $block      = self::getInt4d($this->bigBlockChain, $block * 4);
                }
                return $streamData;
            }
        }
    }
